On September 2, 1998 the aircraft used for the flight, registered HB-IWF, crashed into the Atlantic Ocean southwest of Halifax International Airport at the entrance to St. Margarets Bay, Nova Scotia. The crash site was 8 kilometres (5 mi) from shore, roughly equidistant between the tiny fishing and tourist communities of Peggys Cove and Bayswater. All 229 people on board died.

The resulting investigation by the Transportation Safety Board of Canada (TSB) took over four years and cost CAD$57 million (at that time approximately US$39 million). The organization concluded that flammable material used in the aircraft's structure allowed a fire to spread beyond the control of the crew, resulting in the loss of control and crash of the aircraft.

Swissair Flight 111 was known as the "U.N. shuttle" due to its popularity with United Nations officials; the flight often carried business executives, scientists, and researchers.

History

The aircraft and its crew

The aircraft, a McDonnell DouglasMD-11, serial number 48448 registered
HB-IWF, was manufactured in 1991 and Swissair was its only operator. The airframe had a total of 36,041 hours. The three engines were Pratt & Whitney4462s. The cabin was configured with 241 seats (12 first-, 49 business-, and 180 economy-class). First- and business-class seats were equipped with an in-flight entertainment system.

An MD-11 has a standard flight crew consisting of a captain and a first officer, and a cabin crew made up of a maître de cabine (M/C - purser) supervising the work of 11 flight attendants. All personnel on board Swiss Air Flight 111 were qualified, certified and trained in accordance with Swiss regulations, under the Joint Aviation Authorities (JAA).

The flight

Delta sold the tickets for 53 of the Swissair passengers as part of a codeshare arrangement. Because Air Canada was on strike at the time, some passengers who would have flown on Air Canada instead flew Swissair 111.

At 22:10 Atlantic Time, cruising at FL330, or , the flight crew Captain Urs Zimmermann and First Officer Stephan Loew, detected an odour in the cockpit and determined it to be smoke in the air conditioning system. Four minutes later, the smoke was visible and the pilots began to consider diverting to a nearby airport for the purpose of a quick landing. At 22:14 AT the flight crew made a "pan-pan" radio call, indicating that there was an emergency but no immediate danger to the aircraft, and requested a diversion to Boston's Logan International Airport (300 nautical miles away). Instead, the aircraft was directed to the closer Halifax International Airport in Enfield, Nova Scotia, 66 nm (104 km) away. The crew then put on their oxygen masks and the aircraft began its descent.

At 22:19 AT the plane was away from Halifax airport, but required more time to descend from its altitude of . At 22:20 AT the crew informed ATC that they needed to dump fuel, and the aircraft was subsequently diverted away from the airport. In accordance with the checklist In case of smoke of unknown origin, the crew shut-off the power supply in the cabin, which caused the recirculating fans to shut off. This caused a vacuum which induced the fire to spread back into the cockpit. At 22:24 AT, the crew declared an emergency. Aircraft systems, such as lighting, flight instruments, and the autopilot began to fail and as a result the crew gradually lost control of the aircraft. According to readings from seismographic recorders in Halifax and Moncton, the aircraft struck the ocean at 22:31 AT. The crash location was approximately , with 300 metres' uncertainty.

Recovery and investigation

The aircraft broke up on impact with the water, and most of the debris sank to the ocean floor (a depth of 55 m or 180 ft). Some debris was found floating in the crash area, and over the following weeks debris washed up on the nearby shorelines.

The initial focus of the recovery was on finding and identifying human remains, and on recovering the flight recorders, but this proved difficult as the force of impact was "in the order of at least 350 g",
and the environmental conditions, only allowed recovery along with wreckage.
Only one of the victims was visually identifiable. 147 were identified by fingerprint, dental records, and X-ray comparisons. The remaining 81 were identified through DNA tests.

The cockpit voice recorder (CVR) and flight data recorder (FDR) were found by the submarine Okanagan using sonar to detect the underwater locator beacon signals, and quickly retrieved by Navy divers (the FDR on September 6 and the CVR on September 11, 1998). However, both had stopped recording when the aircraft lost electrical power at approximately , 5 minutes and 37 seconds before impact.

The survey and recovery, dubbed Operation Persistence was TSB guided with resources from the military, CCG, RCMP, and many others. The area was surveyed using route survey sonar, laser line scanners, and remotely operated vehicles to locate items, then recovered (initially by divers and ROV's, later by dredging and trawling).

On October 2, 1998 the Transportation Safety Board of Canada (TSB) initiated a heavy lift operation to retrieve the major portion of the wreckage from the deep water before the expected winter storms began. By October 21, 27% of the wreckage was recovered.

At that point in the investigation, the crash was generally believed to have been caused by faulty wiring in the cockpit, after the entertainment system in the plane started to overheat. Certain groups issued Aviation Safety Recommendations. The TSB released its preliminary report on August 30, 2000, but the final report was not completed until 2003.

The final phase of wreckage recovery employed the ship Queen of the Netherlands to dredge the remaining aircraft debris. It concluded in December 1999 with 98% of the aircraft retrieved: approximately 126,554 kg (279,000 lb) of aircraft debris and 18,144 kg (40,000 lb) of cargo.

Examination

An estimated 2 million pieces of debris were recovered and brought ashore for inspection at a secure handling facility in a marine industrial park at Sheet Harbour, where small material was hand inspected by teams of RCMP officers looking for human remains, personal effects and valuables from the aircraft's cargo hold. The material was then transported to CFB Shearwater where it was assembled and inspected by over 350 investigators from multiple organizations such as TSB, NTSB, FAA, AAIB, Boeing, and Pratt & Whitney.

As each piece of wreckage was brought in, it was carefully cleaned with freshwater, sorted, and weighed. The item was then placed in a specific area of a Hangar at CFB Shearwater, based on a grid system representing the various sections of the plane. All items not considered significant to the crash were stored with similar items in large boxes. When a box was full, it was then weighed and moved to a custom-built temporary structure (J-Hangar) on a discontinued runway for long-term storage. If deemed significant to the investigation, the item was documented, photographed, and kept in the active examination hangar. Particular attention was paid to any item showing heat damage, burns, or other unusual marks.

Cockpit and recordings

The front 10m (33 ft) of the aircraft, from the front of the cockpit to near the front of the first-class passenger cabin, was reconstructed. Information gained by this allowed investigators to determine the severity and limits of the fire damage, its possible origins and progression. The cockpit voice recorder used a 1/4 inch recording tape, operating on a 30 minute loop. It therefore only retained the last half hour of the flight. The CVR recording and transcript are protected by a strict privilege under section 28 of the Canadian Transportation Accident Investigation and Safety Board Act, and thus have not been publicly disclosed. The air traffic control recordings are less strictly privileged: section 29 of the same act provides only that they may not be used in certain legal proceedings. The air traffic control transcripts were released within days of the crash in 1998. The air traffic control audio was released in May 2007.

TSB Findings

The investigation identified eleven causes and contributing factors of the crash in its final report. The first and most important was:

Aircraft certification standards for material flammability were inadequate in that they allowed the use of materials that could be ignited and sustain or propagate fire. Consequently, flammable material propagated a fire that started above the ceiling on the right side of the cockpit near the cockpit rear wall. The fire spread and intensified rapidly to the extent that it degraded aircraft systems and the cockpit environment, and ultimately led to the loss of control of the aircraft.

Arcing from wiring of the in-flight entertainment system network did not trip the circuit breakers. While suggestive, the investigation was unable to confirm if it was this arc was the "lead event" that ignited the flammable covering on insulation blankets that quickly spread across other flammable materials. The crew did not recognize that a fire had started and were not warned by instruments. Once they became aware of the fire, the uncertainty of the problem made it difficult to address. The rapid spread of the fire led to the failure of key display systems, and the crew's ability to control the aircraft was soon overcome. Because he had no light by which to see his controls after the displays failed, the pilot was forced to steer the plane blindly; as a result, the plane swerved off course and headed back out into the Atlantic. Recovered fragments of the plane show that the heat inside the cockpit became so great that the ceiling started to melt.

The recovered standby attitude indicator and airspeed indicator showed that the aircraft struck the water at 300 knots (560km/h, 348 mph) in a 20 degrees nose down and 110 degree bank turn, or almost upside down.
Less than a second after impact the plane would have been totally crushed, killing all aboard almost instantly.

The TSB concluded that even if the crew had been aware of the nature of the problem, the rate at which the fire spread would have precluded a safe landing at Halifax even if an approach had begun as soon as the "pan-pan" was declared.

TSB Recommendations

The TSB made nine recommendations relating to changes in aircraft materials (testing, certification, inspection and maintenance), electrical systems, and flight data capture. (Both flight recorders stopped when they lost power six minutes before impact.) General recommendations were also made regarding improvements in checklists and in fire-detection and fire-fighting equipment and training. These recommendations have led to widespread changes in FAA standards, principally impacting wiring and fire hardening.

The lack of flight recorder data for the last six minutes of the flight added significant complexity to the investigation and was a major factor in its duration. The Transportation Safety Board team had to reconstruct the last six minutes of flight entirely from the physical evidence. The plane was broken into millions of small pieces by the impact, making this process time-consuming and tedious. The investigation became the longest and most expensive transport accident investigation in Canadian history, costing $CAD57 million over five years.

Legacy

Two memorials to those who died on the crash have been established by the government of Canada. One is to the east of the crash site at The Whalesback, a promontory one kilometre (0.6 mile) north of Peggys Cove. The second memorial is a more private but much larger commemoration located west of the crash site near Bayswater Beach Provincial Park on the Aspotogan Peninsula. Here, the unidentified remains of the victims are interred. A fund was established to fund maintenance of the memorials and the government passed an act to recognize them. Various other charitable funds were also created, including one in the name of a young victim from Louisiana, Robert Martin Maillet, which provides money for children in need.

In September 1999 Swissair and Boeing offered the families of the passengers full compensation. The offer was rejected in favor of a $19.8 billion suit against Swissair and DuPont, the supplier of Mylar insulation sheathing. A US federal court dismissed the claim in February 2002.

In May 2007 the TSB released copies of the audio recordings of the air traffic control transmissions associated with the flight. The transcripts of these recordings had been released in 1998 (within days of the crash), but the TSB had refused to release the audio on privacy grounds. The TSB argued that under Canada's Access to Information Act and Privacy Act, the audio recordings constituted personal information and were thus not disclosable. Canada's Federal Court of Appeal rejected this argument in 2006, in a legal proceeding concerned with air traffic control recordings in four other air accidents. The Supreme Court of Canada did not grant leave to appeal that decision, and consequently the TSB released a copy of the Swissair 111 air traffic control audio recordings to Canadian Press, which had requested them under the Access to Information Act. Several key minutes of the air traffic control audio can be found on the Toronto Star web site.